Electrical machine

ABSTRACT

The invention relates to an electrical machine (10), comprising at least one first coil (12), which is surrounded by a first electrical insulation element (24) at least in a partial region, and at least one second coil (14), which is surrounded by a second electrical insulation element (26) at least in a partial region, wherein at least one electrically conductive layer (28) provided in addition to the coils (12, 14) and in addition to the electrical insulation elements (24, 26) is arranged between the coils (12, 14).

The invention relates to an electrical machine, in particular for anaircraft. The invention also relates to an aircraft comprising at leastone electrical machine of this kind.

The development of modern vehicles, such as land vehicles and aircraftfor example, allows for increasing electrification of the drive trainsof the vehicles. This means that the respective drive train has at leastone electrical machine by means of which the respective vehicle can beelectrically driven or which provides a local electrical supply systemon the vehicle (generator). A drive train, by means of which the vehiclecan be, in particular exclusively, driven, is also referred to as anelectrical drive system. In addition to the required power density ofelectrical drive systems of this kind, in particular for aircraft, thefail safety of the drive system has the highest priority. In this case,particular attention should be paid to the short-circuit resistance ofthe respective electrical component or to the detection of a shortcircuit in the component in order to be able to take at least oneprotective measure, such as switching off the drive system for example,as a result of a short circuit of this kind for example.

The object of the present invention is therefore to provide anelectrical machine and a vehicle, so that particularly safe operationcan be implemented.

According to the invention, this object is achieved by an electricalmachine having the features of patent claim 1 and by an aircraft havingthe features of patent claim 14. Advantageous refinements with expedientdevelopments of the invention are specified in the remaining claims.

The electrical machine according to the invention, in particular for avehicle and preferably in particular for an aircraft, which canpreferably be driven by means of the or using the electrical machine,has at least one first coil which is sheathed at least in a subregion bya first electrical insulation. Furthermore, the electrical machineaccording to the present invention has at least one second coil which issheathed at least in a subregion by a second electrical insulation. Therespective electrical insulation is also referred to as a maininsulation since the respective coil is electrically insulated from therespectively other coil and/or from at least one further component ofthe electrical machine by means of the respective associated electricalinsulation. The respective coil itself is an electrical component andhas at least one winding or preferably a plurality of windings whichis/are formed by at least one electrical conductor of the respectivecoil. Electric current can flow through the electrical conductor andtherefore the respective coil in order to in this way at leasttemporarily generate at least one magnetic field, for example by meansof the respective coil.

In order to implement particularly safe operation of the electricalmachine and therefore of the vehicle which is provided, for example, fortransporting people and/or goods per se, at least one electricallyconductive layer, which is provided in addition to the coils and inaddition to the electrical insulations, is arranged between the coils.The electrical machine according to the invention is particularlyadvantageously suitable for use in a vehicle, but the machine canlikewise particularly advantageously be used for other applications.

The feature that the electrically conductive layer is arranged betweenthe coils of the electrical machine is to be understood to mean, inparticular, that the first coil is at least partially, in particular atleast predominantly or completely, covered or overlapped in relation tothe second coil, or vice versa, by the electrically conductive layer, sothat the electrically conductive layer is arranged between respective,mutually facing sides of the coils and in so doing in a manner coveringor overlapping with these sides. If, for example, the main insulation ofone of the coils is damaged, a direct electrical short circuit to therespectively other coil can not only be avoided, but the short circuitor the fault can be transferred to the electrically conductive layer andtherefore, as it were, intercepted by means of the electricallyconductive layer and in particular can be transformed into a faultsituation of the kind that is significantly easier to handle than adirect short circuit between the coils. In this way, excessive damage tothe electrical machine resulting from damage to the main insulation canbe avoided. In particular, total failure of the electrical machine canbe avoided, so that, for example, the electrical machine can continue tobe operated in spite of the damage to the main insulation. As analternative or in addition, it is possible, owing to the use and thearrangement of the electrically conductive layer between the coils, forexcessive damage resulting from damage to the main insulation and, inparticular, total failure of a drive train comprising the electricalmachine for driving the vehicle to be able to be avoided, so thatparticularly safe operation of the vehicle can be ensured by means ofthe electrical machine according to the invention.

The coils are preferably coils which are directly or immediatelyadjacent to one another. This is to be understood as meaning that noother, further coil is arranged between the coils. In this case, theinvention is based on the knowledge that adjacent coils and their supplylines and circuits, in particular in electrical machines for drivingvehicles, can have large differences in the respective electricalpotential. The coils are usually protected or insulated by an electricalinsulation or sufficiently large air gaps. However, in the event of aloss of the insulation property, for example in the case of mechanicaldamage due to environmental influences, improper use, ingress of foreignsubstances such as moisture and/or electrically conductive foreignbodies for example, or aging, short circuits can occur, some of whichhave high short-circuit currents. Owing to their high heat input, theseshort-circuit currents can lead to destruction of the electricalmachine, but this can now be avoided by means of the electrical machineaccording to the invention.

In the case of electrical machines, the short-circuit resistance isusually carried out by means of a robust, time-resistant design of asuitable electrical insulation system of appropriate design and accuratechecking of the insulation during and after manufacture. Checking forsufficient insulation, for example during maintenance of the electricalmachine, can be carried out only with a high level of complexity. Undercertain circumstances, detection of short circuits between individualcoils during operation may not be able to be detected from the outside,in particular at machine terminals, and therefore a local fault may notbe able to be detected. A short circuit can lead to complete destructionof the machine if no detection and consequently no protectiveintervention or no protective measure can take place. In the case of theelectrical machine according to the present invention, at least theprerequisite is now created to avoid the abovementioned problems anddisadvantages, so that particularly safe operation can be implemented.In particular, particularly fail-safe operation can be implemented, andany possible short circuit can be detected without excessive damagewhich is caused by the short circuit occurring. As a result, appropriateprotective measures can be taken to avoid further, excessive damage tothe electrical machine which results from the short circuit.

It has been found to be particularly advantageous when the electricallyconductive layer is arranged within the first insulation between thefirst insulation and the first coil.

In a further advantageous embodiment of the invention, the electricallyconductive layer is arranged outside the first insulation, as a resultof which the first insulation is arranged between the electricallyconductive layer and the first coil. Owing to the respective arrangementof the electrically conductive layer outside or inside the maininsulation, a direct short circuit between the coils can be reliablyprevented, and any short circuit of this kind can be detected in a safeand reliable manner. The electrically conductive layer is preferablyarranged both in a slot region and also in an end winding region of thecoil or its winding in order to be able to reliably prevent a directshort circuit between the coils in this way.

Provision can be made for the electrically conductive layer to bearranged only or exclusively between the two coils, so that theelectrically conductive layer covers or overlaps in each case onlyprecisely one side of one of the coils toward the at least other coil.

However, in order to be able to particularly reliably prevent a directshort circuit between the coils and safely detect a short circuit ofthis kind, it has been found to be advantageous when the electricallyconductive layer surrounds at least a portion of the first coil on atleast two sides which are averted from one another. In particular, thefirst coil is preferably at least predominantly, in particularcompletely, sheathed by the electrically conductive layer. Therefore,for example, the first electrical insulation constitutes a firstsheathing of the first coil, wherein the electrically conductive layerconstitutes a second sheathing of the first coil.

In order to be able to particularly effectively prevent direct shortcircuits between the coils and also to particularly effectively detectany short circuits, provision is made in a further refinement of theinvention for at least one second electrically conductive layer, whichis provided in addition to the coils and in addition to the electricalinsulations, to be arranged between the coils. The electricallyconductive layers are formed, for example, from materials which differfrom one another or by the same material. Where reference is made to theelectrically conductive layer in the text which follows, the statementsmade in this respect can selectively be transferred to the firstelectrically conductive layer and to the second electrically conductivelayer.

The electrically conductive layer is formed, for example, by a solidcomponent, that is to say by a component in the solid state ofaggregation, as a result of which the electrically conductive layer canbe positioned in a particularly advantageous manner.

In order to be able to particularly precisely detect, and for exampleassign, damage to the respective main insulation for example, provisionis made in a further refinement of the invention for the electricallyconductive layers to be electrically insulated from one another by aphase separator which is arranged between the electrically conductivelayers. Particularly safe operation can be ensured in this way.

In a particularly advantageous embodiment of the invention, the secondelectrically conductive layer is arranged within the second insulationbetween the second insulation and the second coil.

It has further been found to be advantageous when the secondelectrically conductive layer surrounds at least a portion of the secondcoil on at least two sides which are averted from one another. Inparticular, the second electrically conductive layer is designed, forexample, as a sheathing of the second coil, so that the second coil isat least partially, in particular at least predominantly or completely,surrounded or sheathed by the second electrically conductive layer.

A further embodiment is distinguished in that the second electricallyconductive layer is arranged outside the second insulation, as a resultof which the second insulation is arranged between the secondelectrically conductive layer and the second coil.

In order to implement particularly safe operation, provision is made ina further refinement of the invention for the electrically conductivelayers to be electrically connected to one another, in particular with ahigh impedance. In other words, a, in particular high-impedance,connection of the or all electrically conductive layers to one anotheris preferably provided.

In order to be able to particularly advantageously detect any damage toat least one of the main insulations, provision is made in a furtherrefinement of the invention for the electrically conductive layers, thatis to say the first electrically conductive layer and/or the secondelectrically conductive layer, to be electrically connected to apredetermined ground potential, in particular with a high impedance. Theground potential is, for example in particular when the vehicle is onthe ground and/or when a connection which provides the ground potentialis electrically connected to the ground, the potential of the ground orthe earth on which the vehicle is standing. Furthermore, it isconceivable for the ground potential to be, in particular when thevehicle is, for example, in the air and therefore not touching theground, a potential of a structure or of a casing of the vehicle,wherein the electrical machine is arranged, for example, in thestructure or in the casing. In particular, the structure or the casingis formed, for example, from a metal material.

In a further refinement of the invention, a detection device isprovided, by means of which detection device an electrical voltagebetween the electrically conductive layer and a reference potential canbe detected. By way of detecting the electrical voltage, a short circuitor damage to at least one of the main insulations can be detected forexample, in particular when the electrical voltage which is detected bymeans of the detection device exceeds, for example, a prespecifiablethreshold value.

In this case, it has been found to be particularly advantageous when thereference potential is the ground potential. In other words, thedetection device renders possible voltage measurement between theelectrically conductive layer and the reference potential, in particularacross a high-impedance grounding resistor. A direct short circuit fromone of the coils to the respectively other coil is also prevented by theelectrically conductive layer in the event of damage to the respectivemain insulation, so that only a short circuit between in each case oneof the coils and the electrically conductive layer can occur. A shortcircuit of this kind can be detected, for example, by means of thedetection device. If a short circuit of this kind is detected by meansof the detection device, at least one protective measure orcountermeasure can be initiated depending on the detection of the shortcircuit, by means of which protective measure or countermeasureundesired effects which result from a short circuit of this kind can beprevented.

If, for example, the electrically conductive layer is a constituent partof an IT network which is a non-grounded system, a fault indicationtakes place, for example, in the event of a short circuit between one ofthe coils and the electrically conductive layer, as a result of whichfault indication the detection device detects that the electricalvoltage which is detected by means of the detection device exceeds aprespecifiable threshold value. The electrical machine is switched off,for example, only in the event of a double fault.

If the electrically conductive layer is, for example, a constituent partof a TN network and therefore of a grounded system, the electricalmachine is switched off, for example, in the event of a short circuitbetween the respective coil and the electrically conductive layer, inparticular when a short circuit of this kind is detected, in particularin such a way that the detection device detects that the electricalvoltage which is detected by means of the detection device exceeds aprespecifiable threshold value.

It has been found to be advantageous when the electrical machine isdesigned to drive the vehicle. The electrical machine can have, forexample, a stator and a rotor which can rotate about a rotation axisrelative to the stator. For example, the rotor can be driven by thestator and in this way can be rotated about the rotation axis relativeto the stator. For example, the electrical machine can be operated as anelectric motor in which the stator drives the rotor. An electricalmachine constitutes a particularly important, if not the most important,part of an electric drive for driving a vehicle, wherein particularlysafe operation of the electrical machine and therefore of the vehicleoverall can be ensured by means of the electrical machine according tothe invention.

It is further possible for the electrical machine to be operated as agenerator. In this case, the rotor is driven by means of mechanicalenergy and in this way rotated about the rotation axis relative to therotor. In the process, the generator converts at least a portion of themechanical energy into electrical energy and makes said electricalenergy available for example. It is further conceivable for theelectrical machine to be designed as a linear machine or as a linearmotor. In this case, the electrical machine has, for example, a statorand a rotor which can be moved relative to the stator along at least orprecisely one axis in a translatory manner. The rotor can be driven bythe stator for example.

The invention also includes an aircraft which has at least oneelectrical machine according to the invention. Advantages andadvantageous refinements of the electrical machine according to theinvention are to be regarded as advantages and advantageous refinementsof the vehicle according to the invention, and vice versa.

Overall, it can be seen that the invention renders possible simpledetection and therefore the possibility of protective intervention or aprotective measure to prevent destruction of the electrical machine. Aprotective measure of this kind may be, for example, switching off adrive, which comprises the electrical machine, for driving the motorvehicle. The electrically conductive layer, which is designed as asheathing of the coil for example, can be very thin, so that the weightand the installation space requirement of the electrical machine can bekept particularly low. This means that the basic installation spacerequirement of the electrical machine changes only slightly from that ofa conventional electrical machine without the electrically conductivelayer, so that, for example, an excessive reduction in the copper fillfactor can be avoided. The electrically conductive layer has a lowelectrical conductivity in order to prevent significant additionallosses due to eddy currents in the electrically conductive layer. Tothis end, the electrically conductive layer is formed, for example, byat least one or more carbon nanotube films and/or at least one or moremica tapes and/or other components. It has further been found that theperformance and the operating behavior of the electrical machineaccording to the invention can remain at least virtually unchanged incomparison to the performance and the operating behavior of aconventional electrical machine, and therefore the electrical machineaccording to the invention also allows high electrical power densitiesfor driving the vehicle to be achieved.

Further advantages, features and details of the invention can begathered from the following description of preferred exemplaryembodiments and with reference to the drawing. The features andcombinations of features cited above in the description and the featuresand combinations of features cited below in the description of thefigures and/or shown in the figures alone can be used not only in therespectively indicated combination but also in other combinations or ontheir own, without departing from the scope of the invention.

In the drawing:

FIG. 1 shows a detail of a schematic sectional view of an electricalmachine according to a first embodiment; and

FIG. 2 shows a detail of a schematic sectional view of the electricalmachine according to a second embodiment.

Identical or functionally identical elements are provided with the samereference symbols in the figures.

FIG. 1 shows a detail of a schematic sectional view of a firstembodiment of an electrical machine 10 for a vehicle, in particular foran aircraft. In this case, the vehicle can be driven by means of theelectrical machine 10. The electrical machine 10 has a stator, not shownin FIG. 1, and a rotor, not shown in FIG. 1, which can be driven by thestator and in this way can be rotated about a rotation axis relative tothe stator. For example, at least one propeller of the aircraft can bedriven by the rotor, so that the aircraft can be made to fly by means ofthe electrical machine 10. In other words, the aircraft can be driven inthe air by means of the electrical machine 10. To this end, theelectrical machine 10 is operated in a motor mode and therefore as anelectric motor. In the motor mode, the rotor and, by means of saidrotor, the propeller are driven by the stator and therefore rotatedabout the rotation axis relative to the stator. Use as a generator, thatis to say an electrical machine which is driven by an internalcombustion engine or turbine for example, is expressly likewise possibleand also covered.

The electrical machine 10 has at least one first coil 12 and at leastone second coil 14 which are wound, for example, onto a laminated core16 of the electrical machine 10. In other words, the coils 12 and 14 arewound around respective subregions of the laminated core 16, so that thecoils 12 and 14 are held on the laminated core 16. To this end, thelaminated core 16 has respective teeth 18, wherein the teeth 18 areimmediately or directly adjacent to one another in the circumferentialdirection, which runs around the rotation axis, of the electricalmachine 10 and therefore of the stator or of the rotor. This means thatno further tooth of the laminated core 16 is arranged between the teeth18 in the circumferential direction of the electrical machine 10. A slot20 of the laminated core 16 is arranged between the teeth 18 in thecircumferential direction of the electrical machine 10, wherein thecoils 12 and 14 are each arranged at least partially in the slot 20.Furthermore, the coil 12 is wound around a first one of the teeth 18,wherein the coil 14 is wound around a second of the teeth 18. Therefore,the coils 12 and 14 are also immediately or directly adjacent to oneanother, so that no other coil or winding of the electrical machine 10is arranged between the adjacent coils 12 and 14 in the circumferentialdirection.

The respective coil 12 or 14 has at least one electrical conductor 22which is formed, for example, from copper, and therefore the conductor22 is designed, for example, as a copper conductor. The respectiveconductor 22 is wound around the tooth 18 in this case, so that in thisway the respective coil 12 or 14 is formed at least by the respectiveconductor 22. The respective conductor 22 is, for example, a partialconductor and provided with a partial conductor insulation and in thisway electrically insulated.

Furthermore, an electrical insulation, which is also referred to as amain insulation 24 or 26, is associated with the respective coil 12 or14. This means that the main insulation 24 is associated with the coil12 and the main insulation 26 is associated with the coil 14, so thatthe coil 12 is electrically insulated by means of the main insulation 24and the coil 14 is electrically insulated by means of the maininsulation 26. It can be seen in FIG. 1 that the respective maininsulation 24 or 26 surrounds at least a length region of therespectively associated coil 12 or 14 completely circumferentially inits circumferential direction, so that at least the respective lengthregion of the respective coil 12 or 14 is sheathed by the respectivemain insulation 24 or 26 completely circumferentially in thecircumferential direction. In particular, the respective coil 12 or 14is at least predominantly, in particular completely, sheathed by therespectively associated main insulation 24 or 26 and in this wayelectrically insulated, in particular toward the respectively other coil14 or 12. The respective main insulation 24 or 26 is therefore alsoreferred to as the first sheathing.

In order to now be able to ensure particularly safe operation of theelectrical machine 10 and therefore of the aircraft overall, a firstelectrically conductive layer 28, which is provided in addition to thecoils 12 and 14 and in addition to the main insulations 24 and 26, isassociated with the coil 12 and therefore the main insulation 24, whichfirst electrically conductive layer is arranged between the coils 12 and14, in particular in the circumferential direction of the electricalmachine 10. Furthermore, a second electrically conductive layer 30,which is provided in addition to the coils 12 and 14, in addition to themain insulations 24 and 26 and in addition to the electricallyconductive layer 28, is associated with the coil 14 and therefore themain insulation 26, which second electrically conductive layer islikewise arranged between the coils 12 and 14. It can be seen in FIG. 1that the respective electrically conductive layer 28 or 30 is designedas a second sheathing of the respective associated coil 12 or 14 in thefirst embodiment shown in FIG. 1. Therefore, the respective secondsheathing surrounds at least a length region of the respective coil 12or 14 completely circumferentially in its circumferential direction. Inparticular, the respective coil 12 or 14 is preferably at leastpartially, in particular at least predominantly or completely, sheathedby the respective second sheathing completely circumferentially in thecircumferential direction. In the first embodiment, the respectivesecond sheathing is arranged outside the respective main insulation 24or 26, so that the main insulation 24 is arranged between the coil 12and the second sheathing (electrically conductive layer 28).Accordingly, the second sheathing (electrically conductive layer 30) isalso arranged outside the main insulation 26, so that the maininsulation 26 is arranged between the coil 14 and the electricallyconductive layer 30 (second sheathing). Furthermore, the electricallyconductive layer 28 is arranged between the electrically conductivelayer 30 and the coil 12, whereas the electrically conductive layer 30is arranged between the electrically conductive layer 28 and the coil14. The respective electrically conductive layer 28 or 30 is preferablyformed by a solid component, that is to say by a component in the solidstate of aggregation. The respective electrically conductive layer 28 or30 can be formed in one piece, or else the respective electricallyconductive layer 28 or 30 has a plurality of parts which are formedseparately from one another and are connected to one another. It isfurther conceivable for the respective electrically conductive layer,respective electrically conductive layer 28 or 30 or the respectivecomponent which forms the respective electrically conductive layer 28 or30 to be designed in a flexible or dimensionally unstable or else rigidor dimensionally stable manner.

Furthermore, provision is made in the case of the electrical machine 10for the electrically conductive layers 28 and 30 to be electricallyconnected to one another with a high impedance. In other words, ahigh-impedance electrical connection 32 is provided, via which theelectrically conductive layers 28 and 30 are electrically connected toone another. To this end, the high-impedance connection 32 has at leastor precisely one electrical resistor R for each electrically conductivelayer 28 or 30 for example. In addition, the electrically conductivelayers 28 and 30 are electrically connected to a predetermined groundpotential 34, so that the electrically conductive layers 28 and 30 are,for example, connected to ground. In other words, a preferablyhigh-impedance ground connection of the electrically conductive layers28 and 30 is provided, in particular in such a way that the electricallyconductive layers 28 and 30 are electrically connected to thepredetermined ground potential 34 with a high impedance and via theresistors R in particular.

In this case, the predetermined ground potential 34 is used as thereference potential in order to detect at least one electrical voltagebetween the electrically conductive layers 28 and 30 and the referencepotential (predetermined ground potential 34) by means of a detectiondevice 36, which is also referred to as a measuring device. In otherwords, the electrical machine 10 comprises the detection device 36, bymeans of which a voltage measurement can be carried out. As part of thevoltage measurement operation, the abovementioned electrical voltagebetween the electrically conductive layers 28 and 30 and thepredetermined ground potential 34 is detected, that is to say measured,by means of the detection device 36. If, for example, the detectiondevice 36 detects that the electrical voltage which is detected by meansof the detection device 36 exceeds a prespecifiable threshold value, ashort circuit between one of the coils 12 and 14 and at least one of theelectrically conductive layers 28 and 30 can be inferred in this way, sothat damage to at least one of the main insulations 24 and 26 can beinferred as a result. Consequently, at least one protective measure orcountermeasure can be carried out, as part of which, for example, theelectrical machine 10 is switched off. Consequently, for example, totalfailure of a drive train, which comprises the electrical machine 10, forelectrically driving the vehicle can be prevented.

The connection 32 further has a busbar 38 to which the electricallyconductive layers 28 and 30 are electrically connected, in particularvia the resistors R. Therefore, the electrically conductive layers 28and 30 and possibly all further electrical layers (not illustrated) ofidentical construction are electrically connected to one another via thebusbar 38. In addition, the electrically conductive layers 28 and 30 areelectrically connected to the predetermined ground potential 34, whichis common to the electrically conductive layers 28 and 30, via thebusbar 38.

FIG. 2 shows a second embodiment of the electrical machine 10. Whereasin the first embodiment the respective electrically conductive layer 28or 30 is designed as a sheathing of the respective coil 12 or 14, sothat in the first embodiment the respective electrically conductivelayer 28 or 30 is arranged on at least two sides of the respective coil12 or 14 which differ from one another and in particular are avertedfrom one another, the respective electrically conductive layer 28 or 30is designed as a substantially two-dimensional layer in the secondembodiment. This means that the respective electrically conductive layer28 or 30 is arranged only on precisely one side of the respective coil12 or 14, so that in the second embodiment in each case only preciselyone side of the respective coil 12 or 14 is covered or overlapped by therespective electrically conductive layer 28 or 30 toward therespectively other coil 14 or 12.

In this case, at least one phase separator 40 is arranged between theelectrically conductive layers 28 and 30 which are electricallyinsulated from one another by means of the phase separator 40.

A further difference between the first embodiment and the secondembodiment is that the coils 12 and 14 which are arranged in the slot 20follow one another in the circumferential direction and in this casedirectly in the first embodiment, so that no other coil is arrangedbetween the coils 12 and 14. In the second embodiment, however, thecoils 12 and 14 are arranged so as to follow one another or one behindthe other in the radial direction of the electrical machine 10, wherein,for example, the coil 14 is at least partially, in particular at leastpredominantly or completely, covered or overlapped by the coil 12 in theradial direction of the electrical machine 10 toward the outside.

Machines which are arranged in a linear manner, for example linearmotors, are not illustrated but are likewise covered by the invention.

1. An electrical machine (10), comprising at least one first coil (12) which is sheathed at least in a subregion by a first electrical insulation (24), and comprising at least one second coil (14) which is sheathed at least in a subregion by a second electrical insulation (26), wherein at least one electrically conductive layer (28), which is provided in addition to the coils (12, 14) and in addition to the electrical insulations (24, 26), is arranged between the coils (12, 14).
 2. The electrical machine (10) as claimed in claim 1, wherein the electrically conductive layer (28) is arranged within the first insulation (24) between said first insulation and the first coil (12).
 3. The electrical machine (10) as claimed in claim 1, wherein the electrically conductive layer (28) is arranged outside the first insulation (24), as a result of which the first insulation (24) is arranged between the electrically conductive layer (28) and the first coil (12).
 4. The electrical machine (10) as claimed in claim 2 or 3, wherein the electrically conductive layer (28) surrounds at least a portion of the first coil (12) on at least two sides which are averted from one another.
 5. The electrical machine (10) as claimed in one of the preceding claims, wherein at least one second electrically conductive layer (30), which is provided in addition to the coils (12, 14) and in addition to the electrical insulations (24, 26), is arranged between the coils (12, 14).
 6. The electrical machine (10) as claimed in claim 5, wherein the electrically conductive layers (28, 30) are electrically insulated from one another by a phase separator (40) which is arranged between said electrically conductive layers.
 7. The electrical machine (10) as claimed in claim 5, wherein the second electrically conductive layer (30) is arranged within the second insulation (26) between said second insulation and the second coil (14).
 8. The electrical machine (10) as claimed in claim 6 or 7, wherein the second electrically conductive layer (30) surrounds at least a portion of the second coil (14) on at least two sides which are averted from one another.
 9. The electrical machine (10) as claimed in one of claims 5 to 8, wherein the second electrically conductive layer (30) is arranged outside the second insulation (26), as a result of which the second insulation (26) is arranged between the second electrically conductive layer (30) and the second coil (14).
 10. The electrical machine (10) as claimed in one of claims 5 to 9, wherein the electrically conductive layers (28, 30) are electrically connected to one another with a high impedance.
 11. The electrical machine (10) as claimed in one of the preceding claims, wherein the electrically conductive layer (28, 30) is electrically connected to a predetermined ground potential (34) with a high impedance.
 12. The electrical machine (10) as claimed in one of the preceding claims, wherein a detection device (36) is provided, by means of which detection device an electrical voltage between the electrically conductive layer (28, 30) and a reference potential (34) can be detected.
 13. The electrical machine (10) as claimed in claims 11 and 12, wherein the reference potential (34) is the ground potential (34).
 14. An aircraft comprising at least one electrical machine (10) as claimed in one of the preceding claims. 